An Indigenous Echelle Grating Spectrograph for Simultaneous Trace Elemental Analysis by Atomic Emission Spectroscopy

Detailed optical design and construction of an indigenously developed echelle grating spectrograph for simultaneous spectrochemical analysis of up to 51 elements by optical emission spectroscopy are presented here. The spectrograph consists of two concave spherical mirrors for collimation and focusing, an echelle grating with groove frequency of 79 lines/mm, and a two-dimensional CCD detector for recording the spectral lines. Fused silica Littrow prism is used for sorting the different spectral orders of 60-120 in the spectrum. The instrument has a wavelength range 200-400 nm with a resolving power of 15,000. The reciprocal linear dispersion of the instrument is 0.353 nm/mm at a wavelength of 300 nm. Results of simultaneous spectrochemical analysis using the inductively coupled plasma source of excitation are also presented.